The converse of "If it snows today, I will ski tomorrow" is "If I ski tomorrow, it snows today". The contrapositive of "If it snows today, I will ski tomorrow" is "If I do not ski tomorrow, it does not snow today". The inverse of "If it snows today, I will ski tomorrow" is "If it does not snow today, I will not ski tomorrow".
The converse of "I come to class whenever there is going to be a quiz" is "If I come to class, there is going to be a quiz". The contrapositive of "I come to class whenever there is going to be a quiz" is "If I do not come to class, there is not going to be a quiz". The inverse of "I come to class whenever there is going to be a quiz" is "I do not come to class whenever there is not going to be a quiz".
The converse of "A positive integer is a prime only if it has no divisors other than 1 and itself" is "If a positive integer has no divisors other than 1 and itself, then it is a prime". The contrapositive of "A positive integer is a prime only if it has no divisors other than 1 and itself" is "If a positive integer is not a prime, then it has divisors other than 1 and itself". The inverse of "A positive integer is a prime only if it has no divisors other than 1 and itself" is "A positive integer is not a prime only if it has divisors other than 1 and itself".